The invention relates to rotary lawn mower blades.
In recent years, it has become less acceptable for lawn mower operators to collect grass clippings, leaves, and other yard debris for dumping in landfills or disposing via other public disposal means. In many regions, regulations prohibit the deposition of yard waste in landfills.
Lawn mower operators have been forced to simply cut their lawn and leave the clippings, chopped leaves, and other yard debris on the lawn. In an effort to minimize the presence of unsightly grass clippings and other unattractive debris on freshly cut lawns, blade manufacturers have developed specialized lawn mower blades. Mulching blades have been developed to mulch the grass into fine clippings that fall to the lawn and settle down out of sight. Shredding blades have been developed to shred leaves, twigs, and other yard waste into small particles that can also settle down in the grass.
The prior art mulching and shredding blades have various problems. Perhaps the largest problem is the inability of mulching blades to adequately shred leaves or yard debris on the lawn, and the inability of shredding blades to mulch the grass underlying the leaves and yard debris. Typically, mulching blades are designed specifically to mulch grass and have only incidental shredding capability. Likewise, shredding blades are designed specifically to shred leaves or debris and have poor grass mulching capability.
Mulching blades require the deck to be closed to keep large grass particles contained until cut into finer pieces. As long as the grass is not too long or the layer of leaves is not too thick, the blade lifts, cuts, mulches, distributes and hides the finely cut grass particles within the cut lawn. In the typical fall scenario, however, the long grass combined with a normal layer of fallen leaves and debris will overload the blade and detract from its capability to cut the grass, the leaves, and the debris into small particles.
Shredding blades are typically used with discharging mower decks. The blade is suited to break up dry, brittle leaves and twigs and discharge them as fine particles. Unfortunately, the features necessary to properly shred the leaves and debris are not well-suited for cutting long grass into fine particles. Grass that is cut by the shredding blade simply gets discharged onto the top of the lawn with the shredded leaf particles. Long grass clippings that are not brittle enough to be shredded often form a bridge between shredders and impede further shredding action.
In light of these problems, the lawn mower operator must decide which blade is best suited to handle the current yard conditions and then use either a mulching blade or a shredding blade to do the job. Depending on the choice made, the lawn will often have improperly shredded leaves and debris, improperly cut grass, or a combination of both. A more precise lawn mower operator may mow the lawn twice, first using a shredding blade on a raised setting to shred the leaves and debris, and then using a mulching blade on a lowered setting to cut the underlying grass. While yielding a better looking end result, this second option more than doubles the time needed to do the job, especially when considering the time required to change the blades.
The present invention solves the above-mentioned problems by providing an improved blade having combined shredding and mulching features. The single blade effectively mulches grass and shreds leaves and debris, allowing the operator to achieve a finely manicured lawn in a single pass. No time is spent deciding on which blade to use or changing blades to suit the condition of the yard. Furthermore, there is no need to undertake separate shredding and mulching passes.
The blade of the present invention can operate with a closed deck to lift and cut grass, comminute grass, lift and shred leaves and distribute finely cut particles into the lawn. Mulching under typical conditions throughout the mowing season is not compromised and mulching in somewhat taller or somewhat wetter conditions is improved. The blade can also be used with a conventional discharge deck to cut grass, partially mulch grass, shred leaves and discharge without compromising the shredding action under typical conditions.
More specifically, the invention provides a rotary lawn mower blade with improved combined mulching and shredding capability. The blade includes an outboard section having a leading cutting edge and a trailing edge. The trailing edge of the outboard section includes a plurality of teeth. The blade also includes a transition section having a leading cutting edge that is at least partially offset relative to the leading cutting edge of the outboard section. The transition section further includes a trailing edge having a partial tooth.
Preferably, the plurality of teeth on the outboard section are twisted in either an inboard or an outboard direction. Additionally, the partial tooth can be twisted in an inboard direction. The plurality of teeth and the partial tooth can each be sharpened or unsharpened.
The blade also preferably includes a central mounting portion and an inboard section between the central mounting portion and the transition section. The inboard section also includes a leading cutting edge and a trailing edge.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.